1. Field of the Invention
The present invention relates to a switch arrangement for holding a load on or off by the inversion of an operable element.
2. Statement of the Prior Art
As illustrated in FIGS. 9 to 11 inclusive, such a type of switch includes a switch element 5 which is turnable around its central axis upon receiving a push at one end. A narrow frame 6 formed on the back side of that element gives a rotational force to a shaft 3 which is in engagement therewith, thereby turning the shaft 3 in the direction counter to the turning of the switch element 5. When grooves 2 in the shaft 3 for supporting a movable frame 7 are horizontally positioned, frame 7 bends an elastic tongue 10 of a lower terminal plate 9. Consequently, a contact 8 rivetted to the central elastic tongue of the movable frame 7 slides over the contact surface of a contact 16 of an upper terminal 15. If the grooves 2 for supporting the movable frame 7 pass over the horizontal line, then the right and left halves of the movable frame 7 move downwardly and upwardly, respectively, due to the restoring force of the elastic tongue 10 of the lower terminal plate 9. At the same time, the contact 16 of the upper terminal 15 is rapidly connected from the contact 8 of the movable frame 7 to shut off the circuit, so that the movable frame 7 comes to a halt, upon abutting a control plate 17. When pushing the other end of the switch element 5, the operation counter to the foregoing operation takes place, so that the contact 8 comes into contact with the contact 16 to close the circuit.
In the switch arrangement as explained in the foregoing, since the movable frame 7 is constantly held between the grooves 2 formed on both sides of the shaft 3 and a notch 11 formed on the upper end of the elastic tongue 10 formed at the middle of the lower terminal plate 9, an amount of heat is generated in notch 11 to interfere with the switching operation of the switch. There is another disadvantage in the above-described switch arrangement in that, since the switch element 5 and shaft 3 are built in a housing 4 into which the terminal plate 9 is fixedly inserted, the assemblage thereof is very cumbersome. In addition, unless the movable frame halves 7 and 7 are provided on both sides of the shaft 3, any stable operation of switching is not attainable.
There is a disadvantage in having an amount of heat generated at a portion for supporting a movable contact, thereby interfering with the operation of switching. For instance, in operating an incandescent lamp, an overcurrent occurs during switching, resulting in arcing. This then leads to fusing of contacts and non-inversion of a switch element, thus making opening of the contacts impossible.